1. Field of the Invention
The present invention relates to a screen-printing method, which is practical for printing a regular color printing on a thin-film material as well as a metal (silver) or pearl color on the thin-film material.
2. Description of the Related Art
A conventional printing method for use in IML hot press, die cutting, and injection molding is a combination of off-set printing and screen-printing includes the steps of off-set printing, four-color design off-set printing, primary screen-printing, baking, secondary screen-printing, baking, hot work die, die cutting, and injection-molding.
At first, use an off-set printing machine to print a single piece base material (thin-film material) with a layer of “transparent thermal bonding agent”. This “transparent thermal bonding agent” makes the base material compatible to the printing ink to be used latter, increasing the bonding power of the printing ink to the base material. The layer of “transparent thermal bonding agent” is then dried by the radiation of a 300 W UV light source of the off-set printing machine. Thereafter, the off-set printing machine is operated to print four-color printing inks or color printing inks assigned by client on the layer of “transparent thermal bonding agent”, enabling the printing inks to be further dried by the radiation of the 300 W UV light source of the off-set printing machine. Thus, the part of off-set printing is finished.
Thereafter, a primary screen-printing procedure is employed to print a printing ink on the workpiece thus obtained through the aforesaid off-set printing procedure. The printing ink is selected subject to the assigned color design, and contains a thermal bonding agent. This primary screen-printing procedure enhances the light tight status and ink bonding power. After the primary screen-printing procedure, the printing is dried in a baking oven at about 75° C.˜85° C. for about 18˜25 minutes. This drying temperature and time may be adjusted subject to the type and thickness of the base material and the type of the printing ink used.
After the aforesaid primary screen-printing, it proceeds to a secondary screen-printing procedure to print a bonding agent on the printing processed through the aforesaid primary screen-printing procedure. This secondary screen-printing procedure is to the bonding power of the printing work during further injection-molding process. After the secondary screen-printing, the printing work is dried in a baking oven at about 75° C.˜85° C. for about 18˜25 minutes. This drying temperature and time may be adjusted subject to the type of the bonding agent used.
After the aforesaid printing procedure, the printing work thus obtained is then treated through a hot work die treatment in a hot press and then cooled down, and then the semi-finished product thus obtained is processed through a die cutting process, and then put in the mold of an injection-molding machine for injection-molding with a plastic material, and the desired finished product is thus obtained.
The aforesaid conventional printing method alternatively employs off-set printing and screen-printing techniques to print printing inks and thermal bonding agent on a thin0film base material. However, because metal (silver) and pearl color printing inks contain shining particles, it is not workable to print metal (silver) and pearl color printing inks on a thin-film base material by an off-set printing machine.